1. Department of Pathology, Inje University Ilsan Paik Hospital, Gyeongggi-do 411-706, Korea.
2. Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
3. Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Korea.